1. Field of the Invention
This invention relates to winders for the continuous production of wound rolls of traveling web material, such as paper. More particularly, this invention relates to apparatus for severing the web in the cross-machine direction while applying adhesive to both the trailing edge of the web being wound into a roll and to the leading edge of the severed web to be wound into a new roll. Still more particularly, this invention relates to a web cross-cutting apparatus for use in conjunction with a winder on a papermaking machine, which apparatus utilizes a laser.
2. Description of the Prior Art
The winder on a papermaking machine receives the on-coming traveling paper web and winds it into a wound roll by attaching the leading edge of the web to a core, which may comprise a metal or paper board spool. The portion of the web trailing from a previously wound roll must be severed in the cross-machine direction before a new roll can be wound by attaching the web to the next core.
Heretofore, the web in a winder was severed in a variety of ways. The web could be slashed by a sharp knife wielded by an operator; it could be snapped off by the tension produced between the wound roll being removed from the winder while the on-coming web was being turned in the opposite direction over a newly inserted core supported by the winder drum, or drums; the web could be severed by a transversely extending knife which was moved against a taut span of the web, or over the web against the surface of a drum and either projected through the web over a slot in the drum surface or held against the drum surface and severed by cutting action or tension against the drum.
All of the prior methods of severing the paper web in a winder operate satisfactorily, but each method and apparatus has its own shortcomings and inefficiencies. In the case where an operator uses a knife, or razor, to manually slash the web across the width of the machine, the machine must be stopped for as long as it takes a person to traverse the width of the web at a location upstream or downstream from the wedge space between the drums. Besides the time involved and the danger of having personnel moving across the width of the machine, the web is not severed in a very straight path and there is a trailing length of paper which hangs loosely after being severed which must either be glued by hand to be attached to the wound roll, or trimmed from an upstream location which has been glued to the wound roll. Also, since the web is severed by hand, the exact location of the severance cannot be known in advance so the leading edge of the severed web either cannot have an adhesive applied automatically, or cannot easily have an adhesive applied to attach it to the next core.
In the case where the web is snapped off from a wound roll, the break profile of the severed web is almost always very ragged and results in wasted paper on both the trailing end of the wound roll and at the leading end of the web to be wound on a new core. Such an unpredictably shaped severance of the web also presents problems in applying an adhesive to both the leading and trailing edges of the severed web.
In the case of using a transversely extending knife, the knife blade usually bears against a winder drum, or the winder drum must be provided with cooperating longitudinally extending notches to accommodate the penetration of the blade through the web. In either case, the drum against which the blade bears must either be notched, which is costly, or is susceptible to being scored due to the frequent contact with the blade. If the severance is effected by moving the blade against a taut span of the web, the exact location of the cut is unpredictable and adhesive cannot be easily and automatically applied to the trailing and leading edges of the unsupported web since it cannot be known in advance where those edges will be located.